test(utils): add JVM unit and composable integration tests for Clustering and WmsTileOverlay

[dkhawk]

Description

Stacked PR on top of #1003 (feature/robolectric-widgets-tests), which stacks on #1001 (feature/robolectric-tests).

Introduces comprehensive JVM unit and Compose integration tests for maps-compose-utils using Robolectric and the local shadow library, raising module line coverage from 2.04% to 69.19% (instruction coverage from 0.78% to 64.11%). Across all three published library modules (maps-compose, maps-compose-widgets, maps-compose-utils), total JVM line coverage reaches 44.95%.

Summary of Changes

• Added test dependencies (robolectric, truth, mockk, androidx.test.compose.ui, maps.robolectric.shadows) to maps-compose-utils/build.gradle.kts.
• Configured Robolectric Android resource processing and Java 21 test runner toolchain.
• Added debug manifest with ComponentActivity for Robolectric Compose rule hosting.
• Added WmsTileOverlayTest.kt verifying WmsTileOverlay composable rendering, tile overlay attributes (transparency, fade-in, visibility, z-index), and tile cache clearing.
• Expanded WmsUrlTileProviderTest.kt covering valid URL formatting and malformed URL handling.
• Added ClusteringTest.kt covering:
  • ClusteringMarkerProperties composition local propagation and mutation.
  • Clustering default renderer marker placement and manager callbacks.
  • Custom Compose UI content rendering (clusterContent, clusterItemContent, clusterItemDecoration).
  • Dynamic item updates (clearing, adding, re-clustering on state change).
  • rememberClusterManager and rememberClusterRenderer lifecycle initialization.

cc @LoyalAbbas @kikoso

[googlemaps-bot]

Code Coverage

Overall Project	24.61%	❌

There is no coverage information present for the Files changed

[github-actions]

Coverage (unit tests)

Compared against a24cc53 on feature/robolectric-widgets-tests (#1000).

Module	Line %	Change	Branch %	Change
maps-compose	36.56%	🔺 +36.56	10.32%	🔺 +10.32
maps-compose-utils	69.19%	🔺 +67.15	24.27%	🔺 +23.78
maps-compose-widgets	67.12%	🔺 +67.12	52.94%	🔺 +52.94
TOTAL	44.95%	🔺 +44.53	14.11%	🔺 +14.02

_{Line and branch coverage from unit test reports. History is recorded in coverage/history.csv after each merge to feature/robolectric-widgets-tests.}